The Effects of Visual and Haptic Vertical Stimulation on Standing Balance in Stroke Patients

OBJECTIVE To explore the effect of visual and haptic vertical stimulation on standing balance in post-stroke patients. METHODS Twenty-five post-stroke patients were recruited. We measured left/right standing pressure differences and the center of pressure (COP) parameters for each patient under three different conditions: no stimulation, visual, and haptic stimulated conditions. First, patients stood on a posturography platform with their eyes blindfolded. After a rest period, the patients stood on the same platform with their eyes fixed to a 1.5-m luminous rod, which was placed at a vertical position in front of the patients. After another rest period, the patients again stood touching a vertically placed long rod in their non-hemiplegic hand with their eyes blindfolded. We collected the signals from the feet in each condition and obtained the balance indices. RESULTS Compared with the no stimulation condition, significant improvements were observed for most of the COP parameters including COP area, length, and velocity for both the visual and haptic vertical stimulation conditions (p<0.01). Additionally, when we compared visual and haptic vertical stimulation, visual vertical stimulation was superior to haptic stimulation for all COP parameters (p<0.01). Left/right standing pressure differences, increased, although patients bore more weight on their paretic side when vertical stimulation was applied (p>0.01). CONCLUSION Both visual and haptic vertical stimulation improved standing steadiness of post-stroke patients. Notably, visual vertical stimulation was more effective than haptic stimulation.